Intrastrand electron and energy transfer between polypyridyl complexes on a soluble polymer
- Univ. of North Carolina, Chapel Hill, NC (United States)
Intrastrand electron and energy transfer between pendant sites in a derivatized 1:1 copolymer of styrene and p-(chloromethyl)styrene have been studied by laser flash photolysis. The polymer [p-PS-Ru[sub 22][sup II]Os[sub 5][sup II]](PF[sub 6])[sub 54], in which 22 of the approximately 27 repeat units of an average strand were Ru[sup II] and 5 Os[sup II], was prepared by nucleophilic displacement of chloride by [M(bpy)[sub 2](bpyCH[sub 2]OH)][sup 2+] (M is Ru or Os: bpy is 2,2[prime]-bipyridine; bpyCH[sub 2]OH is 4-Me-4[prime]-CH[sub 2]OH-2,2[prime]-bipyridine) under basic conditions. Following Ru[sup II] [yields] bpy laser flash excitation there was evidence for a rapid ([tau] < 5 ns) Ru[sup II*] [yields] Os[sup II] energy transfer component with the remaining Ru[sup II*] emission relatively unperturbed compared to [p-PS-Ru[sub 27][sup II]](PF[sub 6])[sub 54]. On the basis of these observations it was inferred that Ru[sup II*] [yields] Os[sup II] energy transfer (which is spontaneous by 0.36 eV) does occur with k(295 [+-] 2K, CH[sub 3]CN) > 2 x 10[sup 8] s[sup [minus]1], but only to Os[sup II] sites that are adjacent to Ru[sup II*]. Energy transfer self-exchange from Ru[sup II*] to Ru[sup II] ([Delta]G[degrees] = 0.0 eV) is slow with k < 1 x 10[sup 6] s[sup [minus]1]. In the presence of 35 mM of the irreversible, oxidative quencher [p-CH[sub 3]OC[sub 6]H[sub 4]N[sub 2]](BF[sub 4]) in CH[sub 3]CN [approximately]94% of the emission from [p-PS-Ru[sup II][sub 22]Os[sup II][sub 5]](PF[sub 6])[sub 54] is quenched. Transient absorption measurements under these conditions show an instantaneous loss of Os[sup II] [yields] bpy, Ru[sup II] [yields] bpy absorption (bleaching) in the visible, consistent with excitation and oxidative quenching during the laser pulse. 43 refs., 9 figs., 1 tab.
- DOE Contract Number:
- FG05-86ER13633
- OSTI ID:
- 6922607
- Journal Information:
- Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 115:16; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
661300 -- Other Aspects of Physical Science-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPLEXES
COPOLYMERS
DECOMPOSITION
DERIVATIZATION
ELECTROMAGNETIC RADIATION
ELECTRON TRANSFER
ENERGY TRANSFER
ENERGY-LEVEL TRANSITIONS
EXCITATION
KINETICS
LASER RADIATION
MATERIALS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
OSMIUM COMPLEXES
OXIDATION
PETROCHEMICALS
PETROLEUM PRODUCTS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PLASTICS
POLYMERS
POLYOLEFINS
POLYSTYRENE
POLYVINYLS
RADIATIONS
REACTION KINETICS
RUTHENIUM COMPLEXES
SYNTHETIC MATERIALS
TRANSITION ELEMENT COMPLEXES